The present invention relates to a bag for protecting a head of an automobile passenger, and, more particularly, to a bag which expands along, for example, a side door window and a B pillar when the automobile crashes at its side surface or turns over and lies on its side. Even more particularly, the present invention relates to a bag for protecting a head of an automobile passenger of a type in which gas enters a main gas path from a gas inlet, and then enters a plurality of small chambers from the main gas path. In addition, the present invention relates to a device for protecting a head of an automobile passenger which includes the bag, and an automobile which includes the device for protecting the head of an automobile passenger.
This type of bag for protecting a head of an automobile passenger is disclosed in WO96/26087. The bag is illustrated particularly in FIGS. 1 and 9 of the patent. The inside of this publicly known bag includes a duct, i.e. main gas path, and a plurality of cells, i.e. small chambers. The duct extends along a top edge of the bag from a front end of the bag, i.e. end of the bag located at a front side of an automobile, to a back end of the bag, i.e. end of the bag located at a back side of the automobile. The cells are connected to the duct, extend downward from the duct, and are arranged from the front end to the back end of the bag.
In the bag disclosed in WO96/26087, a gas flows into the duct from the side of the duct located at the back side of the automobile, and then into each of the plurality of cells. Therefore, it takes time to fill up all of the cells with the gas. In other words, it takes time to finish inflation of the bag. In order to reduce the amount of time required to finish inflation of the bag, it is necessary to increase the gas-generating capacity of the inflator. However, when the gas-generating capacity of the inflator is increased, excess stress is exerted onto the stitches of the bag.
GB2327066A discloses a curtain air bag whose inflation completion time is made shorter by providing X-shaped small chambers in the bag. However, since a large part of the structure of the bag is occupied by the small cells, it is inferred that the actual time required to finish inflation of the bag is not made so short.
Accordingly, it is an object of the present invention to provide a bag for protecting a head of an automobile passenger which makes it possible to sufficiently reduce the time required to finish inflation of the bag without increasing the output of an inflator, and to a protecting device and an automobile which includes the bag.
According to one aspect of the present invention, there is provided a bag for protecting a head of an automobile passenger which is disposed near a corner of an automobile where a side surface and a ceiling inside the automobile intersect and which expands downward along the side surface of the automobile as a result of gas entering the bag from a gas inlet. The bag comprises a top side disposed along the ceiling of the automobile, a main air path which is connected to the gas inlet, and a cushion including chambers which expand as a result of gas entering into the cushion from the main air path. The cushion includes a small upper chamber which extends along the top side in a direction of a line extending from the main air path, with one end of the small upper chamber being connected to the main air path, a small side chamber which is connected to the other end of the small upper chamber so as to extend downward, a small lower chamber which extends along a bottom side of the bag, with one end of the small lower chamber being connected to the small side chamber, and a small intermediate chamber which is disposed between and connected to the small lower chamber and the small upper chamber, and which is separated from the small side chamber.
In such a bag for protecting the head of an automobile passenger, the gas flowing into the main air path from the inlet flows rapidly into the cushion. The flow of the gas inside the cushion spreads to cause the small upper chamber and the small intermediate chamber to expand rapidly. After the small upper chamber and the small intermediate chamber have expanded, the gas which has passed through the small upper chamber collides with the inside wall of the cushion, smoothly changes its direction of flow, and flows into the small side chamber. On the other hand, the gas which has passed through the small intermediate chamber collides with the inside wall of the cushion, smoothly changes its direction of flow, and flows into the small lower chamber. Thereafter, from either one of the small side chamber and the small lower chamber that has finished expansion earlier, the gas flows into the other small side chamber or the small lower chamber. When the other chamber has expanded, the expansion of the cushion is completed. The small side chamber and the small lower chamber may finish expansion at about the same time.
Accordingly, at the initial stage of expansion, the small intermediate chamber and the small upper chamber close to the main air path expand rapidly. The small side chamber and the small lower chamber expand by the gas which has passed through the small upper chamber and the small intermediate chamber. Here, since the small upper chamber and the small intermediate chamber have already expanded to a sufficiently large size, the gas flows smoothly, so that a sufficient gas pressure is also applied to the small side chamber and the small lower chamber, which expand rapidly. Therefore, the cushion as a whole expands in a very short time. Accordingly, the time required to complete the expansion of the whole bag is made considerably less than that of conventional bags in which every cell is expanded.
In the present invention, it is preferable that the bag for protecting the head of an automobile passenger further comprises a front side disposed along an A pillar of the automobile, and a back side disposed along either a C pillar or a D pillar. In the bag, the main gas path extends along the front side and a front portion of the top side, and the gas inlet is formed in a lower portion of the front side.
In the present invention, in the bag for protecting the head of an automobile passenger comprising a front side and a back side, it is preferable that the cushion is disposed near an intermediate portion of the bag in a forward and backward direction along the automobile and is located near a B pillar and a back portion of a front-door window adjacent to the B pillar. In the bag, curtains which do not expand are provided between the cushion and the front side of the bag and between the cushion and the back side of the bag, respectively.
In such a bag, when the cushion expands, the curtains disposed at the front and back of the cushion are in a taut state. As a result, even if a door window opens, the cushion is not pushed out of the vehicle from the door window, and the head of a passenger is prevented from projecting out of the vehicle. Since the cushion is only disposed at the intermediate portion of the bag in the forward or backward direction, the cushion finishes expansion in a considerable short time.
According to another aspect of the present invention, there is provided a device for protecting a head of an automobile passenger comprising: any one of the bags explained above for protecting the head of an automobile passenger, and an inflator connected to the gas inlet of the bag.
According to still another aspect of the present invention, there is provided an automobile comprising the device for protecting the head of the automobile passenger.